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| United States Patent |
5,658,667
|
|
Yoshida
, et al.
|
August 19, 1997
|
Thermal transfer recording material
Abstract
A thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation, the vehicle comprising not less than 85% by weight of an epoxy
resin, the epoxy resin comprising not less than 50% by weight of at least
one of tetraphenolethane tetraglycidyl ether and a bromide thereof, cresol
novolac polyglycidyl ether and a bromide thereof, and bisphenol F
diglycidyl ether and a bromide thereof. The recording material has
excellent transferability and gives printed images excellent heat
resistance, solvent resistance and scratch resistance.
| Inventors:
|
Yoshida; Katsuhiro (Osaka, JP);
Akashiro; Kotaro (Osaka, JP)
|
| Assignee:
|
Fujicopian Co., Ltd. (Osaka, JP)
|
| Appl. No.:
|
505470 |
| Filed:
|
July 21, 1995 |
Foreign Application Priority Data
| Jul 22, 1994[JP] | 6-171271 |
| Aug 31, 1994[JP] | 6-207302 |
| Sep 16, 1994[JP] | 6-221417 |
| Oct 13, 1994[JP] | 6-247963 |
| Nov 08, 1994[JP] | 6-273611 |
| Dec 20, 1994[JP] | 6-316946 |
| May 01, 1995[JP] | 7-107556 |
| May 01, 1995[JP] | 7-107557 |
| May 01, 1995[JP] | 7-107558 |
| May 01, 1995[JP] | 7-107559 |
| Current U.S. Class: |
428/32.6; 428/32.76; 428/32.83; 428/207; 428/211.1; 428/913 |
| Intern'l Class: |
B41M 005/26 |
| Field of Search: |
428/195,207,211,413,484,488.1,913
|
References Cited
U.S. Patent Documents
| 5290623 | Mar., 1994 | Kawahito et al. | 428/195.
|
| Foreign Patent Documents |
| 0 412 517 | Feb., 1991 | EP | .
|
| 0 444 641 | Sep., 1991 | EP | .
|
| 60-59159 | Dec., 1985 | JP | .
|
| 60-059 159 | Dec., 1985 | JP | .
|
| 7-172070 | Jul., 1995 | JP | .
|
Other References
Translation-in-part of Japanese unexamined patent publication 7-172070,
published Jul. 11, 1995, filed Aug. 3, 1994.
Derwent Database Abstract, No. 87-104 184, citing Japanese patent
application 62-50360, published Mar. 5, 1987.
Derwent Database Abstract, No. 89-160 081, citing Japanese patent
application 1-100749, published Apr. 19, 1989.
|
Primary Examiner: Schwartz; Pamela R.
Attorney, Agent or Firm: Fish & Neave
Claims
What we claim is:
1. A thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation,
the vehicle comprising not less than 85% by weight of an epoxy resin,
the epoxy resin comprising not less than 50% by weight of at least one of
tetraphenolethane tetraglycidyl ether and a bromide thereof.
2. The thermal transfer recording material of claim 1, wherein the content
of the epoxy resin in the vehicle is not less than 95% by weight.
3. The thermal transfer recording material of claim 1, which further
comprises a layer comprising a wax provided between the foundation and the
heat-meltable ink layer, the layer comprising the wax having a penetration
of not more than 1.
4. A thermal transfer recording material for forming a color image
comprising at least one region wherein a color is developed by virtue of
subtractive color mixture of at least two superimposed inks selected from
a yellow heat-meltable ink, a magenta heat-meltable ink and cyan
heat-meltable ink,
the thermal transfer recording material comprising a foundation, and a
yellow heat-meltable ink layer, a magenta heat-meltable ink layer and a
cyan heat-meltable ink layer provided on the foundation in a side-by-side
relation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment, the vehicle comprising not less than 85% by weight of an
epoxy resin, the epoxy resin comprising not less than 50% by weight of at
least one of tetraphenolethane tetraglycidyl ether and a bromide thereof.
5. An assembly of plural thermal transfer recording materials for forming a
color image comprising at least one region wherein a color is developed by
virtue of subtractive color mixture of at least two superimposed inks
selected from a yellow heat-meltable ink, a magenta heat-meltable ink and
cyan heat-meltable ink,
the assembly comprising a first thermal transfer recording material
comprising a foundation, and a yellow heat-meltable ink layer provided on
the foundation, a second thermal transfer recording material comprising a
foundation, and a magenta heat-meltable ink layer provided on the
foundation, and a third thermal transfer recording material comprising a
foundation, and a cyan heat-meltable ink layer provided on the foundation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment provided on the foundation, the vehicle comprising not less
than 85% by weight of an epoxy resin, the epoxy resin comprising not less
than 50% by weight of at least one of tetraphenolethane tetraglycidyl
ether and a bromide thereof.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer recording material.
More particularly, the present invention relates to a thermal transfer
recording material for use in forming printed images having excellent heat
resistance, solvent resistance, scratch resistance, and like properties.
Conventional common thermal transfer recording materials include one
wherein a heat-meltable ink containing a wax as the main component of the
vehicle thereof is applied on a foundation, and another wherein a
heat-meltable ink containing a resin as the main component of the vehicle
thereof, for the purpose of forming printed images of high quality even on
a paper sheet having poor surface smoothness or forming printed images
having good fastness.
Recently, bar code printers or label printers using a thermal transfer
recording material have been used for printing bar codes or like codes
which are used for management of parts or products in production process
of manufacturing factories, merchandise management in distribution field,
management of articles in use field, and the like.
Among such articles to be given bar codes, there are those exposed to high
temperatures after provision of bar codes. For example, a heat treatment
at about 180.degree. C. is conducted in production process for printed
wiring bards and a heat treatment at about 250.degree. C. in inspection
process for semiconductors.
Bar codes or like codes used for product management in manufacturing
factories or the like require good solvent resistance because they
frequently come into contact with solvents, oils and the like, and bar
codes or like codes used in distribution field or the like require good
scratch resistance because they are frequently subjected to rubbing.
Further, besides printing bar codes, thermal transfer printers have been
used for production of multi-product in small quantities, including
outdoor advertising, election posters, general posters, standing
signboards, stickers, catalogs, pamphlets, calender, and the like in
commercial printing field; bags for light packaging, labels for containers
for foods, drinks, medicines, paints, and the like, and binding tapes in
packaging field; labels for indicating quality characteristic, labels for
process control, labels for product management, and the like in apparel
field. These articles also require scratch resistance, solvent resistance
or heat resistance.
However, there are no conventional thermal transfer recording materials
which have excellent transferability and can form printed images meeting
such heat resistance, solvent resistance and scratch resistance at the
same time.
That is, although the above-mentioned conventional thermal transfer
recording material with a heat-meltable ink layer whose vehicle is
composed of a wax as a main component is good in transferability, the
printed images obtained therefrom are sometimes collapsed when exposed to
a high temperature of about 250.degree. C. to become illegible, and are
also poor in solvent resistance and scratch resistance. The
above-mentioned conventional thermal transfer recording material with a
heat-meltable ink layer whose vehicle is composed of a resin, such as
ethylene-vinyl acetate copolymer, as a main component forms printed images
which are comparatively good in heat resistance, solvent resistance and
scratch resistance, but its transferability is inferior to that of the
recording medium having the wax-predominant ink layer because of the high
melt viscosity of its ink layer.
Further, a thermal transfer recording material using a heat-meltable ink
containing bisphenol A diglycidyl ether as a vehicle is proposed (Japanese
Examined Patent Publication No. 60-59159). However, this bisphenol A type
epoxy resin has a disadvantage that a pigment such as carbon black is not
favorably dispersed thereinto. For this reason, the recording material is
poor in transferability, resulting in unclear printed images. With respect
to recording materials for use in thermal transfer recording system, poor
transferability is a fatal drawback.
An object of the present invention is to provide a thermal transfer
recording material which has excellent transferability and can form
printed images which have such heat resistance that they stand high
temperatures up to about 280.degree. C., and further have excellent
solvent resistance and scratch resistance.
This and other objects of the present invention will become apparent from
the description hereinafter.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention, there is provided a
thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation,
the vehicle comprising not less than 85% by weight of an epoxy resin,
the epoxy resin comprising not less than 50% by weight of at least one of
tetraphenolethane tetraglycidyl ether and a bromide thereof.
In an embodiment of the first aspect, the content of the epoxy resin in the
vehicle is not less than 95% by weight.
In another embodiment of the first aspect, the thermal transfer recording
material further comprises a layer comprising a wax provided between the
foundation and the heat-meltable ink layer, the layer comprising the wax
having a penetration of not more than 1.
In still another embodiment of the first aspect, there is provided a
thermal transfer recording material for forming a color image comprising
at least one region wherein a color is developed by virtue of subtractive
color mixture of at least two superimposed inks selected from a yellow
heat-meltable ink, a magenta heat-meltable ink and cyan heat-meltable ink,
the thermal transfer recording material comprising a foundation, and a
yellow heat-meltable ink layer, a magenta heat-meltable ink layer and a
cyan heat-meltable ink layer provided on the foundation in a side-by-side
relation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment, the vehicle comprising not less than 85% by weight of an
epoxy resin, the epoxy resin comprising not less than 50% by weight of at
least one of tetraphenolethane tetraglycidyl ether and a bromide thereof.
In a further embodiment of the first aspect, there is provided an assembly
of plural thermal transfer recording materials for forming a color image
comprising at least one region wherein a color is developed by virtue of
subtractive color mixture of at least two superimposed inks selected from
a yellow heat-meltable ink, a magenta heat-meltable ink and cyan
heat-meltable ink,
the assembly comprising a first thermal transfer recording material
comprising a foundation, and a yellow heat-meltable ink layer provided on
the foundation, a second thermal transfer recording material comprising a
foundation, and a magenta heat-meltable ink layer provided on the
foundation, and a third thermal transfer recording material comprising a
foundation, and a cyan heat-meltable ink layer provided on the foundation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment provided on the foundation, the vehicle comprising not less
than 85% by weight of an epoxy resin, the epoxy resin comprising not less
than 50% by weight of at least one of tetraphenolethane tetraglycidyl
ether and a bromide thereof.
According to the second aspect of the present invention, there is provided
a thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation,
the vehicle comprising not less than 85% by weight of an epoxy resin,
the epoxy resin comprising not less than 50% by weight of at least one of
cresol novolac polyglycidyl ether and a bromide thereof.
In an embodiment of the second aspect, the content of the epoxy resin in
the vehicle is not less than 95% by weight.
In another embodiment of the second aspect, the thermal transfer recording
material further comprises a layer comprising a wax provided between the
foundation and the heat-meltable ink layer, the layer comprising the wax
having a penetration of not more than 1.
In still another embodiment of the second aspect, there is provided a
thermal transfer recording material for forming a color image comprising
at least one region wherein a color is developed by virtue of subtractive
color mixture of at least two superimposed inks selected from a yellow
heat-meltable ink, a magenta heat-meltable ink and cyan heat-meltable ink,
the thermal transfer recording material comprising a foundation, and a
yellow heat-meltable ink layer, a magenta heat-meltable ink layer and a
cyan heat-meltable ink layer provided on the foundation in a side-by-side
relation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment, the vehicle comprising not less than 85% by weight of an
epoxy resin, the epoxy resin comprising not less than 50% by weight of at
least one of cresol novolac polyglycidyl ether and a bromide thereof.
In a further embodiment of the second embodiment, there is provided an
assembly of plural thermal transfer recording materials for forming a
color image comprising at least one region wherein a color is developed by
virtue of subtractive color mixture of at least two superimposed inks
selected from a yellow heat-meltable ink, a magenta heat-meltable ink and
cyan heat-meltable ink,
the assembly comprising a first thermal transfer recording material
comprising a foundation, and a yellow heat-meltable ink layer provided on
the foundation, a second thermal transfer recording material comprising a
foundation, and a magenta heat-meltable ink layer provided on the
foundation, and a third thermal transfer recording material comprising a
foundation, and a cyan heat-meltable ink layer provided on the foundation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment provided on the foundation, the vehicle comprising not less
than 85% by weight of an epoxy resin, the epoxy resin comprising not less
than 50% by weight of at least one of cresol novolac polyglycidyl ether
and a bromide thereof.
According to the third aspect of the present invention, there is provided a
thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation,
the vehicle comprising not less than 85% by weight of an epoxy resin,
the epoxy resin comprising not less than 50% by weight of at least one of
bisphenol F diglycidyl ether and a bromide thereof.
In an embodiment of the third aspect, the content of the epoxy resin in the
vehicle is not less than 95% by weight.
In another embodiment of the third aspect, the bisphenol F diglycidyl ether
is represented by formula (V):
##STR1##
wherein m1 is an integer of 0 to 33, and the bromide is represented by the
formula (VI):
##STR2##
wherein m2 is an integer of 0 to 33, and q1, q2, q3 and q4 are
independently an integer of 1 or 2.
In still another embodiment of the third aspect, the total amount of the
bisphenol F diglycidyl ether of formula (V) wherein m1 is 0 and/or the
bromide of formula (VI) wherein m2 is 0 is not more than 2% by weight of
the total amount of the bisphenol F diglycidyl ether of formula (V) and/or
the bromide of formula (VI).
In a further embodiment of the third aspect, thermal transfer recording
material further comprises a layer comprising a wax provided between the
foundation and the heat-meltable ink layer, the layer comprising the wax
having a penetration of not more than 1.
In a still further embodiment of the third aspect, there is provided a
thermal transfer recording material for forming a color image comprising
at least one region wherein a color is developed by virtue of subtractive
color mixture of at least two superimposed inks selected from a yellow
heat-meltable ink, a magenta heat-meltable ink and cyan heat-meltable ink,
the thermal transfer recording material comprising a foundation, and a
yellow heat-meltable ink layer, a magenta heat-meltable ink layer and a
cyan heat-meltable ink layer provided on the foundation in a side-by-side
relation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment, the vehicle comprising not less than 85% by weight of an
epoxy resin, the epoxy resin comprising not less than 50% by weight of at
least one of bisphenol F diglycidyl ether and a bromide thereof.
In a more still further embodiment of the third aspect, there is provided
an assembly of plural thermal transfer recording materials for forming a
color image comprising at least one region wherein a color is developed by
virtue of subtractive color mixture of at least two superimposed inks
selected from a yellow heat-meltable ink, a magenta heat-meltable ink and
cyan heat-meltable ink,
the assembly comprising a first thermal transfer recording material
comprising a foundation, and a yellow heat-meltable ink layer provided on
the foundation, a second thermal transfer recording material comprising a
foundation, and a magenta heat-meltable ink layer provided on the
foundation, and a third thermal transfer recording material comprising a
foundation, and a cyan heat-meltable ink layer provided on the foundation,
each of the respective color heat-meltable ink layers comprising a vehicle
and a pigment provided on the foundation, the vehicle comprising not less
than 85% by weight of an epoxy resin, the epoxy resin comprising not less
than 50% by weight of at least one of bisphenol F diglycidyl ether and a
bromide thereof.
According to the fourth aspect of the present invention, there is provided
a thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation,
the vehicle comprising not less than 85% by weight of an epoxy resin,
the pigment having an oil absorption of not less than 80.
In an embodiment of the fourth aspect, the epoxy resin is at least one of
bisphenol A diglycidyl ether and a bromide thereof.
In another embodiment of the fourth aspect, the thermal transfer recording
material further comprises a layer comprising a wax provided between the
foundation and the heat-meltable ink layer, the layer comprising the wax
having a penetration of not more than 1.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a partial plan view showing an example of arrangement of
respective color ink layers in an embodiment of the thermal transfer
recording material of the present invention.
DETAILED DESCRIPTION
The first aspect of the present invention will be explained below.
Tetraphenolethane tetraglycidyl ether (hereinafter referred to as "TPETGE"
as the need arises) used in the first aspect is a type of polyfunctional
epoxy resin represented by formula (I):
##STR3##
TPETGE has a softening point of 92.degree. C.
A bromide of TPETGE (hereinafter referred to as "Br-TPETGE" as the need
arises) used in the first aspect includes, for example, one represented by
formula (II):
##STR4##
wherein p is usually an integer of 1 or 2. The bromine atom is usually
substituted at the ortho position of the benzene ring with respect to the
glycidoxy group.
According to the first aspect of the present invention wherein, in a
thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation, the vehicle comprises not less than 85% (% by weight,
hereinafter the same) of an epoxy resin, and the epoxy resin comprises not
less than 50% of at least one of TPETGE and Br-TPETGE, the ability of the
vehicle for dispersing a pigment thereinto is improved so that the
transferability of the ink is improved, resulting in clear printed images,
and the resulting printed images stand a high temperature up to about
280.degree. C. and have excellent solvent resistance and scratch
resistance.
According to the first embodiment of the first aspect wherein the content
of the epoxy resin in the vehicle is not less than 95%, the heat
resistance, solvent resistance and scratch resistance of the resulting
printed images are further improved.
According to the second embodiment of the first aspect wherein a wax layer
having a penetration of not more than 1 is provided between the foundation
and the heat-meltable ink layer, the scratch resistance of the resulting
printed images are further improved.
With use of the thermal transfer recording materials for color image
formation according to the third and fourth embodiments of the first
aspect, there are obtained printed images which have excellent heat
resistance, scratch resistance and solvent resistance as well as excellent
color reproducibility because of good superimposition of respective color
heat-meltable ink layers.
The heat-meltable ink used in the first aspect of the present invention
comprises a vehicle and a pigment. The vehicle comprises an epoxy resin
and the epoxy resin contains not less than 50%, preferably not less than
70 %, of at least one of TPETGE and Br-TPETGE.
In the first aspect, the whole resin component in the vehicle may be
composed of at least one of TPETGE sad Br-TPETGE. This is not essential.
The desired effect is exhibited so long as an epoxy resin component
containing not less than 50% of at least one of TPETGE and Br-TPETGE is
used. When the content of TPETGE and/or Br-TPETGE in total in the whole
epoxy resin component is less than the above range, the dispersibility of
a pigment into the vehicle is degraded, resulting in poor transferability.
The content of an epoxy resin component containing not less than 50% of at
least one of TPETGE and Br-TPETGE in the vehicle is not less than 85%,
preferably not less than 95%. When the content of the epoxy resin
component in the vehicle is less than the above range, the desired effect
is prone not to be exhibited.
The use of Br-TPETGE as the main component of the vehicle of the
heat-meltable ink layer in the first aspect imparts flame resistance to
the ink layer. For example, an ink layer having flame resistance passing
UL Standard (UL-94V-O) can be obtained. Therefore, a thermal transfer
recording material wherein a heat-meltable ink layer containing Br-TPETGE
is provided on a flame-resistant foundation can be safely used in a
high-temperature environment. In the case of a printed product obtained by
forming printed images of a heat-meltable ink containing Br-TPETGE on a
flame-resistant receptor, the printed images do not disappear even in a
higher-temperature environment or even when exposed to flame.
Examples of epoxy resins usable together with TPETGE and/or Br-TPETGE in
the first aspect of the present invention are as follows:
(1) Glycidyl ether type
Examples of epoxy resins of this type are bisphenol A diglycidyl ether,
bisphenol F diglycidyl ether, brominated bisphenol A diglycidyl ether,
brominated bisphenol F diglycidyl ether, hydrogenated bisphenol A
diglycidyl ether, novolac polyglycidyl ether, cresol novolac polyglycidyl
ether, glycerol triglycidyl ether, pentaerythritol diglycidyl ether, and
the like.
(2) Glycidyl ether ester type
Examples of epoxy resins of this type are p-oxybenzoic acid diglycidyl
ether ester, and the like.
(3) Glycidyl ester type
Examples of epoxy resins of this type are phthalic acid diglycidyl ester,
tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid
diglycidyl ester, dimer acid diglycidyl ester, and the like.
(4) Glycidyl amine type
Examples of epoxy resins of this type are glycidylaniline, triglycidyl
isocyanurate, and the like.
(5) Linear aliphatic epoxy type
Examples of epoxy resins of this type are epoxidized polybutadiene,
epoxidized soybean oil, and the like.
(6) Alicyclic epoxy type
Examples of epoxy resins of this type are
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylat
e, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and the like.
The above-mentioned other epoxy resins can be used singly or as a mixture
of two or more species thereof. Preferable as the other epoxy resins are
those having a softening point of not less than 60.degree. C. However, an
epoxy resin in a liquid state can also be used so long as, when it is
mixed with epoxy resins other than it, including TPETGE and Br-TPETGE, the
resulting vehicle has a softening point of not less than 60.degree. C.
The above-mentioned vehicle may be incorporated with one or more
heat-meltable resins other than epoxy resins unless the purpose of the
present invention is injured. Examples of such heat-meltable resins are
ethylene-vinyl acetate copolymer resin, ethylene-alkyl (meth)acrylate
copolymer resin, phenol resin, styreneacrylic monomer copolymer resin,
polyester resin and polyamide resin. Preferably, such heat-meltable resin
is used in an amount of not more than 15%, more preferably not more than
5%, on the basis of the total amount of the vehicle.
The softening point of the vehicle is preferably from 60.degree. to
120.degree. C. in view of the storage stability and transferability of the
thermal transfer recording material.
The content of the vehicle in the heat-meltable ink is preferably from 40
to 95% by weight in view of the transferability and a like property.
The second aspect of the present invention will be explained below.
Cresol novolac polyglycidyl ether (hereinafter referred to as "CNPGE" as
the need arises) used in the second aspect is a type of polyfunctional
epoxy resin. Preferred is one represented by formula (III):
##STR5##
wherein k1 is usually an integer of 3 to 7. CNPGE used in the present
invention includes a mixture of those of formula (III) wherein the values
for k1 are different from each other. CNPGE preferably has a softening
point of 60.degree. to 120.degree. C.
A bromide of CNPGE (hereinafter referred to as "Br-CNPGE" as the need
arises) used in the second aspect includes, for example, one represented
by formula (IV):
##STR6##
wherein k2 is usually an integer of 3 to 7. Br-CNPGE used in the second
aspect includes a mixture of those of formula (IV) wherein the values for
k2 are different from each other. Br-CNPGE preferably has a softening
point of 60.degree. to 120.degree. C.
According to the second aspect of the present invention wherein, in a
thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation, the vehicle comprise not less than 85% of an epoxy resin, and
the epoxy resin comprises not less than 50% of at least one of CNPGE and
Br-CNPGE, the ability of the vehicle for dispersing a pigment thereinto is
improved so that the transferability of the ink is improved, resulting in
clear printed images, and the resulting printed images stand a high
temperature up to about 280.degree. C. and have excellent solvent
resistance and scratch resistance.
According to the first embodiment of the second aspect wherein the content
of the epoxy resin in the vehicle is not less than 95%, the heat
resistance, solvent resistance and scratch resistance of the resulting
printed images are further improved.
According to the second embodiment of the second aspect wherein a wax layer
having a penetration of not more than 1 is provided between the foundation
and the heat-meltable ink layer, the scratch resistance of the resulting
printed images are further improved.
With use of the thermal transfer recording materials for color image
formation according to the third and fourth embodiments of the second
aspect, there are obtained printed images which have excellent heat
resistance, scratch resistance and solvent resistance as well as excellent
color reproducibility because of good superimposition of respective color
heat-meltable ink layers.
The heat-meltable ink used in the second aspect of the present invention
comprises a vehicle and a pigment. The vehicle comprises an epoxy resin
and the epoxy resin contains not less than 50%, preferably not less than
70%, of at least one of CNPGE and Br-CNPGE.
In the second aspect, the whole resin component in the vehicle may be
composed of at least one of CNPGE and Br-CNPGE. This is not essential. The
desired effect is exhibited so long as an epoxy resin component containing
not less than 50% of at least one of CNPGE and Br-CNPGE is used. When the
content of CNPGE and/or Br-CNPGE in total in the whole epoxy resin
component is less than the above range, the dispersibility of a pigment
into the vehicle is degraded, resulting in poor transferability.
The content of an epoxy resin component containing not less than 50% of at
least one of CNPGE and Br-CNPGE in the vehicle is not less than 85%,
preferably not less than 95%. When the content of the epoxy resin
component in the vehicle is less than the above range, the desired effect
is prone not to be exhibited.
The use of Br-CNPGE as the main component of the vehicle of the
heat-meltable ink layer in the second aspect imparts flame resistance to
the ink layer. For example, an ink layer having flame resistance passing
UL Standard (UL-94V-O) can be obtained. Therefore, a thermal transfer
recording material wherein a heat-meltable ink layer containing Br-CNPGE
is provided on a flame-resistant foundation can be safely used in a
high-temperature environment. In the case of a printed product obtained by
forming printed images of a heat-meltable ink containing Br-CNPGE on a
flame-resistant receptor, the printed images do not disappear even in a
higher-temperature environment or even when exposed to flame.
Examples of epoxy resins usable together with CNPGE and/or Br-CNPGE in the
second aspect of the present invention are as follows:
(1) Glycidyl ether type
Examples of epoxy resins of this type are bisphenol A diglycidyl ether,
bisphenol F diglycidyl ether, brominated bisphenol A diglycidyl ether,
brominated bisphenol F diglycidyl ether, hydrogenated bisphenol A
diglycidyl ether, novolac polyglycidyl ether, glycerol triglycidyl ether,
pentaerythritol diglycidyl ether, tetraphenolethane tetraglycidyl ether,
and the like.
(2) Glycidyl ether ester type
Examples of epoxy resins of this type are p-oxybenzoic acid diglycidyl
ether ester, and the like.
(3) Glycidyl ester type
Examples of epoxy resins of this type are phthalic acid diglycidyl ester,
tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid
diglycidyl ester, dimer acid diglycidyl ester, and the like.
(4) Glycidyl amine type
Examples of epoxy resins of this type are glycidylaniline, triglycidyl
isocyanurate, and the like.
(5) Linear aliphatic epoxy type
Examples of epoxy resins of this type are epoxidized polybutadiene,
epoxidized soybean oil, and the like.
(6) Alicyclic epoxy type
Examples of epoxy resins of this type are
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylat
e, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and the like.
The above-mentioned other epoxy resins can be used singly or as a mixture
of two or more species thereof. Preferable as the other epoxy resins are
those having a softening point of not less than 60.degree. C. However, an
epoxy resin in a liquid state can also be used so long as, when it is
mixed with epoxy resins other than it, including CNPGE and Br-CNPGE, the
resulting vehicle has a softening point of not less than 60.degree. C.
The above-mentioned vehicle may be incorporated with one or more
heat-meltable resins other than epoxy resins unless the purpose of the
present invention is injured. Examples of such heat-meltable resins are
ethylene-vinyl acetate copolymer resin, ethylene-alkyl (meth)acrylate
copolymer resin, phenol resin, styreneacrylic monomer copolymer resin,
polyester resin and polyamide resin. Preferably, such heat-meltable resin
is used in an amount of not more than 15%, more preferably not more than
5%, on the basis of the total amount of the vehicle.
The softening point of the vehicle is preferably from 60.degree. to
120.degree. C. in view of the storage stability and transferability of the
thermal transfer recording material.
The content of the vehicle in the heat-meltable ink is preferably from 40
to 95% by weight in view of the transferability and a like property.
The third aspect of the present invention will be explained below.
Bisphenol F diglycidyl ether (hereinafter referred to as "BPFDGE" as the
need arises) used in the third aspect is a type of difunctional epoxy
resin. Preferred is one represented by formula (V):
##STR7##
wherein m1 is usually an integer of 0 to 33. BPFDGE used in the present
invention includes a mixture of those of formula (V) wherein the values
for m1 are different from each other.
BPFDGE preferably has a softening point of 60.degree. to 140.degree. C.
A bromide of BPFDGE (hereinafter referred to as "Br-BPFDGE" as the need
arises) used in the third aspect includes, for example, one represented by
formula (VI):
##STR8##
wherein m2 is usually an integer of 0 to 33, and q1, q2, q3 and q4 are
independently an integer of 1 or 2. In formula (VI), the bromine atom is
usually substituted at the meta position of the benzene ring with respect
to the methylene group of the bisphenol F skelton. Br-BPFDGE used in the
third aspect includes a mixture of those of formula (VI) wherein the
values for m2 are different from each other. Br-BPFDGE preferably has a
softening point of 60.degree. to 140.degree. C. A typical example of
Br-BPFDGE is one represented by formula (VII):
##STR9##
wherein m2 is the same as in formula (VI).
According to the third aspect of the present invention wherein, in a
thermal transfer recording material comprising a foundation and a
heat-meltable ink layer comprising a vehicle and a pigment provided on the
foundation, the vehicle comprises not less than 85% of an epoxy resin, and
the epoxy resin comprises not less than 50% of at least one of BPFDGE and
Br-BPFDGE, the ability of the vehicle for dispersing a pigment thereinto
is improved so that the transferability of the ink is improved, resulting
in clear printed images, and the resulting printed images stand a high
temperature up to about 280.degree. C. and have excellent solvent
resistance (against solvents such as kerosene, gasoline, ethanol, toluene
and carbon tetrachloride) and scratch resistance.
According to the first embodiment of the third aspect wherein the content
of the epoxy resin in the vehicle is not less than 95% by weight, the heat
resistance, solvent resistance and scratch resistance of the resulting
printed images are further improved.
According to the second embodiment of the third aspect wherein BPFDGE is
specified to one represented by formula (V) and Br-BPFDGE is specified to
one represented by formula (VI), excellent transferability and like
properties are assured.
According to the third embodiment of the third aspect wherein the total
amount of BPFDGE of formula (V) wherein m1 is 0 and/or Br-BPFDGE of
formula (VI) wherein m2 is 0 is not more than 2% of the total amount of
BPFDGE of formula (V) and/or Br-BPFDGE formula (Vl), the ethanol
resistance and toluene resistance of the resulting printed images are
further improved.
According to the fourth embodiment of the third aspect wherein a wax layer
having a penetration of not more than 1 is provided between the foundation
and the heat-meltable ink layer, the toluene resistance and scratch
resistance of the resulting printed images are further improved.
With use of the thermal transfer recording materials for color image
formation according to the fifth and sixth embodiments of the third
aspect, there are obtained printed images which have excellent heat
resistance, scratch resistance and solvent resistance as well as excellent
color reproducibility because of good superimposition of respective color
heat-meltable ink layers.
The heat-meltable ink used in the third aspect of the present invention
comprises a vehicle and a pigment. The vehicle comprises an epoxy resin
and the epoxy resin contains not less than 50%, preferably not less than
70%, of at least one of BPFDGE and Br-BPFDGE.
In the third aspect, the whole resin component in the vehicle may be
composed of at least one of BPFDGE and Br-BPFDGE. This is not essential.
The desired effect is exhibited so long as an epoxy resin component
containing not less than 50% of at least one of BPFDGE and Br-BPFDGE is
used. Although a vehicle composed of at least one of BPFDGE and Br-BPFDGE
together with other epoxy resin provides considerably improved results,
the vehicle does not necessarily provide satisfactory solvent resistance
and dispersibility of a pigment into the vehicle, the latter resulting in
undesirable transferability. Accordingly, it is especially preferable to
use an epoxy resin component composed of BPFDGE and/or Br-BPFDGE alone.
When the content of BPFDGE and/or Br-BPFDGE in total in the whole epoxy
resin component is less than the above range, the dispersibility of a
pigment into the vehicle is degraded, resulting in poor transferability.
The content of an epoxy resin component containing not less than 50% of at
least one of BPFDGE and Br-BPFDGE in the vehicle is not less than 85%,
preferably not less than 95%. When the content of the epoxy resin
component in the vehicle is less than the above range, the desired effect
is prone not to be exhibited.
In the third aspect, it is preferable that the total mount of BPFDGE of
formula (V) wherein m1 is 0 and/or Br-BPFDGE of formula (VI) wherein m2 is
0 is not more than 2%, more preferably not more than 1.5%, of the total
mount of BPFDGE of formula (V) and/or Br-BPFDGE of formula (VI). When the
total mount of BPFDGE of formula (V) wherein m1=0 and/or Br-BPFDGE of
formula (VI) wherein m2=0 is more than the above range, solvent
resistance, particularly ethanol resistance and toluene resistance, is not
satisfactorily improved.
The use of Br-BPFDGE as the main component of the vehicle of the
heat-meltable ink layer in the third aspect imparts flame resistance to
the ink layer. For example, an ink layer having flame resistance passing
UL Standard (UL-94V-O) can be obtained. Therefore, a thermal transfer
recording material wherein a heat-meltable ink layer containing Br-BPFDGE
is provided on a flame-resistant foundation can be safely used in a
high-temperature environment. In the case of a printed product obtained by
forming printed images of a heat-meltable ink containing Br-BPFDGE on a
flame-resistant receptor, the printed images do not disappear even in a
higher-temperature environment or even when exposed to flame.
Examples of epoxy resins usable together with BPFDGE and/or Br-BPFDGE in
the third aspect of the present invention are as follows:
(1) Glycidyl ether type
Examples of epoxy resins of this type are bisphenol A diglycidyl ether,
brominated bisphenol A diglycidyl ether, hydrogenated bisphenol A
diglycidyl ether, novolac polyglycidyl ether, cresol novolac polyglycidyl
ether, glycerol triglycidyl ether, pentaerythritol diglycidyl ether,
tetraphenolethane tetraglycidyl ether, and the like.
(2) Glycidyl ether ester type
Examples of epoxy resins of this type are p-oxybenzoic acid diglycidyl
ether ester, and the like.
(3) Glycidyl ester type
Examples of epoxy resins of this type are phthalic acid diglycidyl ester,
tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid
diglycidyl ester, dimer acid diglycidyl ester, and the like.
(4) Glycidyl amine type
Examples of epoxy resins of this type are glycidylaniline, triglycidyl
isocyanurate, and the like.
(5) Linear aliphatic epoxy type
Examples of epoxy resins of this type are epoxidized polybutadiene,
epoxidized soybean oil, and the like.
(6) Alicyclic epoxy type
Examples of epoxy resins of this type are
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylat
e, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and the like.
The above-mentioned other epoxy resins can be used singly or as a mixture
of two or more species thereof. Preferable as the other epoxy resins are
those having a softening point of not less than 60.degree. C. However, an
epoxy resin in a liquid state can also be used so long as, when it is
mixed with epoxy resins other than it, including BPFDGE and Br-BPFDGE, the
resulting vehicle has a softening point of not less than 60.degree. C.
The above-mentioned vehicle may be incorporated with one or more
heat-meltable resins other than epoxy resins unless the purpose of the
present invention is injured. Examples of such heat-meltable resins are
ethylene-vinyl acetate copolymer resin, ethylene-alkyl (meth)acrylate
copolymer resin, phenol resin, styreneacrylic monomer copolymer resin,
polyester resin and polyamide resin. Preferably, such heat-meltable resin
is used in an amount of not more than 15%, more preferably not more than
5%, on the basis of the total amount of the vehicle.
The softening point of the vehicle is preferably from 60.degree. to
120.degree. C. in view of the storage stability and transferability of the
thermal transfer recording material.
The content of the vehicle in the heat-meltable ink is preferably from 40
to 95% by weight in view of the transferability and a like property.
The fourth aspect of the present invention will be explained below.
As described previously, generally, bisphenol A diglycidyl ether is poor in
ability of dispersing a pigment such as carbon black thereinto. In the
present invention, however, it has been found that a pigment, such as
carbon black, having an oil absorption of not less than 80 is unexpectedly
favorably dispersed into bisphenol A diglycidyl ether and/or a bromide of
bisphenol A diglycidyl ether.
Herein, the term "oil absorption" of a pigment means the mount (m1) of
dibutyl phthalate which 100 g of a pigment absorbs.
A heat-meltable ink obtained by dispersing a pigment having an oil
absorption of not less than 80 into bisphenol F diglycidyl ether and/or
its bromide provides an excellent transferability because the pigment is
uniformly dispersed therein, resulting in clear printed images having a
high density.
When a pigment having an oil absorption of not less than 80 is dispersed
into an epoxy resin other than bisphenol F diglycidyl ether or its
bromide, the dispersibility of the pigment is also improved. However, when
a pigment having an oil absorption of not less than 80 is dispersed into
bisphenol F diglycidyl ether and/or its bromide, the dispersibility of the
pigment is markedly improved.
The heat-meltable ink used in the fourth aspect of the present invention
comprises a vehicle and a pigment. The vehicle comprises not less than 85%
of an epoxy resin and the pigment has an oil absorption of not less than
80. The use of a pigment having an excessively large oil absorption
provides an ink coating liquid having poor flowability, resulting in poor
coating property. From this point of view, a pigment having an oil
absorption of not more than about 330 is preferably used.
The heat-meltable ink layer has excellent transferability because the
pigment is uniformly dispersed therein, resulting in clear printed images
of a high density, and the resulting printed images stand a
high-temperature up to about 280.degree. C. about and have excellent
solvent resistance against solvents such as kerosene, gasoline, ethanol
and carbon tetrachloride, and excellent scratch resistance because the
vehicle contains not less than 85% of an epoxy resin.
When the content of the epoxy resin in the vehicle is less than 85%, in
particular, the scratch resistance is degraded.
According to the first embodiment of the fourth aspect wherein the total
mount of bisphenol A diglycidyl ether and/or a bromide thereof is not less
than 50%, preferably, substantially 100% of the total amount of the epoxy
resin component, the above-mentioned effect of improving the
dispersibility of the pigment is markedly exhibited.
Bisphenol A diglycidyl ether (hereinafter referred to as "BPADGE" as the
need arises) used in the fourth aspect is a type of difunctional epoxy
resin. Preferred is one represented by formula (VII):
##STR10##
wherein n1 is usually an integer of 0 to 13. BPADGE used in the present
invention includes a mixture of those of formula (VIII) wherein the values
for n1 are different from each other. BPADGE preferably has a softening
point of 60.degree. to 140.degree. C.
A bromide of BPADGE (hereinafter referred to as "Br-BPADGE" as the need
arises) used in the fourth aspect includes, for example, one represented
by formula (IX):
##STR11##
wherein n2 is usually an integer of 0 to 13, and r1, r2, r3 and r4 are
independently an integer of 1 or 2. In formula (IX), the bromine atom is
usually substituted at the meta position of the benzene ring with respect
to the methylene group of the bisphenol A skelton. Br-BPADGE used in the
fourth aspect includes a mixture of those of formula (IX) wherein the
values for n2 are different from each other. Br-BPADGE preferably has a
softening point of 60.degree. to 140.degree. C. A typical example of
Br-BPADGE is one represented by formula (X):
##STR12##
wherein n2 is the same as in formula (IX).
According to the second embodiment of the fourth aspect wherein a wax layer
having a penetration of not more than 1 is provided between the foundation
and the heat-meltable ink layer, the scratch resistance of the resulting
printed images are further improved.
The use of Br-BPADGE as the main component of the vehicle of the
heat-meltable ink layer in the fourth aspect imparts flame resistance to
the ink layer. For example, an ink layer having flame resistance passing
UL Standard (UL-94V-O) can be obtained. Therefore, a thermal transfer
recording material wherein a heat-meltable ink layer containing Br-BPADGE
is provided on a flame-resistant foundation can be safely used in a
high-temperature environment. In the case of a printed product obtained by
forming printed images of a heat-meltable ink containing Br-BPADGE on a
flame-resistant receptor, the printed images do not disappear even in a
higher-temperature environment or even when exposed to flame.
Examples of epoxy resins usable singly or together with BPADGE and/or
Br-BPADGE in the fourth aspect of the present invention are as follows:
(1) Glycidyl ether type
Examples of epoxy resins of this type are bisphenol F diglycidyl ether,
brominated bisphenol F diglycidyl ether, hydrogenated bisphenol A
diglycidyl ether, novolac polyglycidyl ether, cresol novolac polyglycidyl
ether, glycerol triglycidyl ether, pentaerythritol diglycidyl ether,
tetraphenolethane tetraglycidyl ether, and the like.
(2) Glycidyl ether ester type
Examples of epoxy resins of this type are p-oxybenzoic acid diglycidyl
ether ester, and the like.
(3) Glycidyl ester type
Examples of epoxy resins of this type are phthalic acid diglycidyl ester,
tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid
diglycidyl ester, dimer acid diglycidyl ester, and the like.
(4) Glycidyl amine type
Examples of epoxy resins of this type are glycidylaniline, triglycidyl
isocyanurate, and the like.
(5) Linear aliphatic epoxy type
Examples of epoxy resins of this type are epoxidized polybutadiene,
epoxidized soybean oil, and the like.
(6) Alicyclic epoxy type
Examples of epoxy resins of this type are
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylat
e, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and the like.
The above-mentioned epoxy resins can be used singly or as a mixture of two
or more species thereof. Preferable as the epoxy resins are those having a
softening point of not less than 60.degree. C. However, an epoxy resin in
a liquid state can also be used so long as, when it is mixed with epoxy
resins other than it, including BPADGE and Br-BPADGE, the resulting
vehicle has a softening point of not less than 60.degree. C.
The above-mentioned vehicle may be incorporated with one or more
heat-meltable resins other than epoxy resins unless the purpose of the
present invention is injured. Examples of such heat-meltable resins are
ethylene-vinyl acetate copolymer resin, ethylene-alkyl (meth)acrylate
copolymer resin, phenol resin, styrene-acrylic monomer copolymer resin,
polyester resin and polyamide resin. Preferably, such heat-meltable resin
is used in an amount of not more than 15%, more preferably not more than
5%, on the basis of the total amount of the vehicle.
The softening point of the vehicle is preferably from 60.degree. to
120.degree. C. in view of the storage stability and transferability of the
thermal transfer recording material.
The content of the vehicle in the heat-meltable ink is preferably from 40
to 95% by weight in view of the transferability and a like property.
Usable as a pigment in the fourth aspect are those having an oil absorption
of not less than 80, preferably not less than 110. A pigment having an oil
absorption of less than the above range provides poor dispersibility
against epoxy resins, particularly BPADGE and/or Br-BPADGE.
Hereinafter, descriptions common to the first, second, third and fourth
aspects of the present invention will be given unless otherwise noted.
Usable as the pigment for the heat-meltable ink in the present invention
are various organic and inorganic pigments as well as carbon black.
Examples of organic and inorganic pigments are azo pigments (such as
insoluble azo pigments, azo lake pigments and condensed azo pigments),
phthalocyanine pigments, nitro pigments, nitroso pigments, anthraquinonoid
pigments, nigrosine pigments, quinacridone pigments, perylene pigments,
isoindolinone pigments, dioxazine pigments, titanium white, calcium
carbonate and barium sulfate. The content of the pigment in the ink layer
is preferably from 5 to 60%.
Yellow pigments, magenta pigments, and cyan pigments, and optionally black
pigments are used for forming multi-color or full-color printed images
utilizing subtractive color mixture.
The pigments for yellow, magenta and cyan as used in the ink layer are
preferably transparent ones. Usable as the black pigments are usually
opaque ones.
Examples of transparent yellow pigments include organic pigments such as
Naphthol Yellow S, Hansa Yellow 5G, Hansa Yellow 3G, Hansa Yellow G, Hansa
Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Benzidine
Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG and
Quinoline Yellow Lake. These pigments may be used singly or in combination
of two or more species thereof.
Examples of transparent magenta pigments include organic pigments such as
Permanent Red 4R, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent
Carmine FB, Lithol Red, Permanent Red F5R, Brilliant Carmine 6B, Pigment
Scarlet 3B, Rhodamine Lake B, Rhodamine Lake Y, Arizalin Lake and
Quinacridone Red. These pigments may be used singly or in combination of
two or more species thereof.
Examples of transparent cyan pigments include organic pigments such as
Victoria Blue Lake, metal-free Phthalocyanine Blue, Phthalocyanine Blue
and Fast Sky Blue. These pigments may be used singly or in combination of
two or more species thereof.
The term "transparent pigment" is herein meant by a pigment which gives a
transparent ink when dispersed in a transparent vehicle.
Examples of the black pigments include inorganic pigments such as carbon
black, and organic pigments such as Aniline Black. These pigments may be
used singly or in combination of two or more species thereof.
In the fourth aspect of the present invention, pigments having an oil
absorption of not less than 80 are used.
The content of the pigment in each of the respective color ink layers is
usually from about 5 to about 60%.
The heat-meltable ink layer used in the present invention can be
incorporated with additives such as dispersing agent, besides the
above-mentioned components.
The heat-meltable ink layer in the present invention can be formed by
applying a coating liquid prepared by dissolving the above-mentioned
vehicle components into a solvent and dissolving or dispersing the pigment
and other additives, followed by drying. The coating amount (on a solid
basis, hereinafter the same) of the heat-meltable ink layer in the present
invention is preferably from 0.02 to 5 g/m.sup.2, more preferably from 0.5
to 3 g/m.sup.2.
As the foundation for the thermal transfer recording material of the
present invention, there can be used polyester films such as polyethylene
terephthalate film, polybutylene terephthalate film, polyethylene
naphthalate film and polyarylate film, polycarbonate film, polyamide film,
aramid film, polyether sulfone film, polysulfone film, polyphenylene
sulfide film, polyether ether ketone film, polyether imide film, modified
polyphenylene ether film and poyacetal film, and other various plastic
films commonly used for the foundation of ink ribbons of this type. Thin
paper sheets of high density such as condenser paper can also be used. The
thickness of the foundation is usually from about 1 to about 10 .mu.m.
From the view point of reducing heat spreading to increase the resolution
of printed images, the thickness of the foundation is preferably from 1 to
6 .mu.m.
In the case that the thermal transfer recording material of the present
invention is used in a thermal transfer printer equipped with a thermal
head, a conventionally known stick-preventive layer is preferably provided
on the back side (the side adapted to come into slide contact with the
thermal head) of the foundation. Examples of the materials for the
stick-preventive layer include various heat-resistant resins such as
silicone resins, fluorine-containing and nitrocellulose resins, and other
resins modified with these heat-resistant resins, such as
silicone-modified urethane resins and silicone-modified acrylic resins,
and mixtures of the foregoing heat-resistant resins and lubricating
agents.
In the preferred embodiment of the present invention, a wax layer having a
penetration of not more than 1 is provided between the foundation and the
heat-meltable ink layer. With the printed image obtained by using the
thermal transfer recording material of such construction, the surface of
the printed image is covered with the colorless hard wax layer having a
penetration of not more than 1 and, hence, the scratch resistance of the
printed image is further improved due to good lubricity of the surface of
the wax layer and the protection effect by the wax layer. The resistance
to ethanol is also further improved. When a wax layer having a penetration
of more than 1 is used, the scratch resistance is rather degraded.
Herein, the penetration is measured at 25.degree. C. according to the
penetration measuring method provided in JIS K 2235.
Usable as the wax for the wax layer are carnauba wax, polyethylene wax, and
the like. These waxes can be used singly or in combination.
The wax layer can be formed by applying a solvent solution, solvent
dispersion or aqueous emulsion of the wax onto the foundation, followed by
drying. The wax layer can also be formed by a hot-melt coating method.
The coating amount of the wax layer is usually from 0.01 to 2.0 g/m.sup.2,
preferably from 0.1 to 1.0 g/m.sup.2. When the coating amount of the wax
layer is less than the above range, the desired effect is not sufficiently
exhibited. When the coating amount of the wax layer is more than the above
range, the transferability is degraded in some cases.
The thermal transfer recording material of the present invention includes a
thermal transfer recording material for forming a monochromatic image and
a thermal transfer recording material for forming a multi-color or
full-color image utilizing subtractive color mixture.
The thermal transfer recording material for forming a monochromatic image
has a structure wherein a monochromatic heat-meltable ink layer is
provided on a foundation. Examples of the color for the heat-meltable ink
layer are black, red, blue, green, yellow, magenta and cyan.
An embodiment of the color thermal transfer recording material for forming
a multi-color or full-color image has a structure wherein on a single
foundation are disposed a yellow heat-meltable ink layer, a magenta
heat-meltable ink layer and a cyan heat-meltable ink layer, and,
optionally, a black heat-meltable ink layer in a side-by-side relation.
Various manners can be adopted for disposing the respective color ink
layers on the foundation and a suitable manner is determined depending
upon the kind of printer.
FIG. 1 is a partial plan view showing an example of the thermal transfer
recording material in accordance with the aforesaid embodiment. In FIG. 1,
on a single foundation 1 are disposed a yellow heat-meltable ink layer 2Y,
a magenta heat-meltable ink layer 2M and a cyan heat-meltable ink layer 2C
in a side-by-side relation The ink layer 2Y, the ink layer 2M and the ink
layer 2C, each of which has a predetermined constant size, are
periodically repeatedly disposed in a side-by-side relation in the
longitudinal direction of the foundation 1 in a repeating unit U
comprising the ink layers 2Y, 2M and 2C arranged in a predetermined order.
The order of arrangement of these three color ink layers in the repeating
unit U can be suitably determined according to the order of transfer of
the respective color ink layers. A black ink layer may be included in the
repeating unit U.
Another embodiment of the color thermal transfer recording material for
forming a multi-color or full-color image is a set comprising a first
thermal transfer recording material wherein a yellow heat-meltable ink
layer is provided on a foundation, a second thermal transfer recording
material wherein a magenta heat-meltable ink layer is provided on a
foundation, and a third thermal transfer recording material wherein a cyan
heat-meltable ink layer is provided on a foundation, and, optionally, a
fourth thermal transfer recording material wherein a black heat-meltable
ink layer is provided on a foundation.
The use of each of the aforesaid thermal transfer recording materials can
give a multi-color or full-color image having excellent heat resistance,
scratch resistance and solvent resistance. Further, the respective color
heat-meltable ink layers in the present invention are excellent in
superimposing property, resulting in a multi-color or full-color image
having excellent color reproducibility.
When the wax layer is provided between the foundation and each color ink
layer, the superimposing property of the respective color ink layers is
prone to be degraded, and, hence, it is preferable not to provide the wax
layer in the thermal transfer recording material for color image
formation.
The formation of printed images with use of the thermal transfer recording
material of the present invention can be performed by superimposing the
ink layer of the thermal transfer recording material onto an
image-receiving body and applying imagewise heat energy to the ink layer.
A thermal head is generally used as a heat source for the heat energy.
However, any conventional heat sources such as laser light, infrared flash
and heat pen can be used.
When the image-receiving body is not a sheet-like material but a
three-dimensional article, or one having a curved surface, thermal
transfer using laser light is advantageous.
The formation of a multi-color or full-color image with use of the thermal
transfer recording material of the present invention is preferably
performed as follows: With use of a thermal transfer printer, the yellow
ink layer, the magenta ink layer and the cyan ink layer are selectively
melt-transferred onto a receptor in a predetermined order according to
separation color signals of an original multi-color or full-color image,
i.e. yellow signals, magenta signals and cyan signals to form yellow ink
dots, magenta ink dots and cyan ink dots on the receptor in a
predetermined order, yielding a yellow separation image, a magenta
separation image and a cyan separation image superimposed on the receptor.
The order of transfer of the yellow ink layer, the magenta ink layer and
the cyan ink layer can be determined as desired. When a usual full-color
or multi-color image is formed, all the three color ink layers are
selectively transferred according to three color signals to form three
color separation images on the receptor. When only two color signals are
present, the corresponding two of the three color ink layers are
selectively transferred to form two color separation images of a yellow
separation image, a magenta separation image and a cyan separation image.
Thus there is obtained a multi-color or full-color image comprising (A) at
least one region wherein a color is developed by virtue of subtractive
color mixture of at least two superimposed inks of yellow, magenta and
cyan, or (B) a combination of the region (A), and at least one region of
single color selected from yellow, magenta and cyan wherein different
color inks are not superimposed. Herein a region where yellow ink dots and
magenta ink dots are present in a superimposed state develops a red color;
a region where yellow ink dots and cyan ink dots are present in a
superimposed state develops a green color; a region where magenta ink dots
and cyan ink dots are present in a superimposed state develops a blue
color; and a region where yellow ink dots, magenta ink dots and cyan ink
dots are present in a superimposed state develops a black color. A region
where only yellow ink dots, magenta ink dots or cyan ink dots are present
in a non-superimposed state develops a yellow color, a magenta color or a
cyan color.
In the above manner, a black color is developed by the superimposing of
yellow ink dots, magenta ink dots and cyan ink dots. However, a black
color may be obtained by using only black ink dots instead of using three
color ink dots. In that case, the black color may be obtained by
superimposing black ink dots on at least one of yellow ink dots, magenta
ink dots and cyan ink dots, or on superimposed ink dots of at least two of
yellow ink dots, magenta ink dots and cyan ink dots.
The thermal transfer recording material of the present invention is
favorably used for forming printed images on an object which is subjected
to a heat treatment at a temperature of not less than 150.degree. C.,
because the recording material gives printed images having excellent heat
resistance as described above. When the temperature for the heat treatment
which an object is subjected to is too high, the vehicle component of the
printed image is prone to be decomposed so that the shape as the printed
image is lost. Therefore, it is preferable that the temperature for the
heat treatment which the object is subjected to is not more than about
280.degree. C.
In the case of forming printed images with use of the thermal transfer
recording material, printed images may be directly formed on a final
object.
Alternatively, printed images may be previously formed on a sheet-like
image-receiving body (receptor) and then the image-receiving body with the
printed images formed is attached to a final object with a suitable means
such as heat-resistant adhesive.
Various sheet-like articles can be used as the aforesaid sheet-like
receptor. However, the sheet-like receptor disclosed in the applicant's
prior Japanese Patent Application No. 141996/1994 is suitably used. The
receptor comprises a foundation, an image-receiving layer provided on one
side of the foundation and composed of a white pigment and an organic
binder as essential components, and a heat-resistant pressure-sensitive
adhesive layer provided on the other side of the foundation. The organic
binder is phenoxy resin, or a mixture of phenoxy resin and saturated
polyester resin. Other examples of the sheet-like receptor are sheets of
heat-resistant resins such as polyimide, cloths of glass fibers or ceramic
fibers, sheets wherein the foregoing cloths are coated with or impregnated
with a heat-resistant resin, glass or ceramic sheets, and metal sheets.
The printed images formed on an object with use of the thermal transfer
recording material of the present invention are further substantially
improved in the heat resistance, solvent resistance and scratch resistance
by being subjected to a heat treatment. The heat treatment is preferably
performed by heating the printed images in an atmosphere of 150.degree. to
250.degree. C. for 15 to 60 minutes. It is presumed that the epoxy resin
contained in the printed images is cross-linked by such heat treatment,
thereby improving the fastness of the printed images.
In the case of printed images formed on an article, such as printed wiring
board or semiconductor, which is subjected to heating treatment equivalent
to the aforesaid heat treatment in a later step, the heat treatment is not
necessarily required.
The thermal transfer recording material of the present invention is
especially advantageously used for forming printed images on articles
which are subjected to a heating treatment at high temperatures of about
150.degree. to about 280.degree. C., such as printed wiring bards which
are subjected to such heating treatment in production process and
semiconductors which are subjected to such heating treatment in inspection
process, because the recording material gives printed images having
excellent heat resistance, solvent resistance and scratch resistance.
The present invention will be more fully described by way of Examples. It
is to be understood that the present invention is not limited to the
Examples, and various change and modifications may be made in the
invention without departing from the spirit and scope thereof.
EXAMPLES 1-1 TO 1-10 AND COMPARATIVE EXAMPLES 1-1 to 1-3
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer was applied an ink coating liquid having the formula shown in Table
1-1, followed by drying to form a heat-meltable ink layer with a coating
amount of 2 g/m.sup.2, yielding a thermal transfer recording material.
TABLE 1-1
__________________________________________________________________________
Com. Com.
Com.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex. Ex. Ex. Ex.
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
1-1 1-2 1-3
__________________________________________________________________________
Formula of ink coating liquid (%)
Epikote 1031S*.sup.1
14 18 8 11 11 7 12.6
14 14 14 5
Epikote 1003*.sup.2 3 7 14 9
Epikote 828*.sup.3 3
Paraffin wax 16
Ethylene-vinyl 1.4 2
acetate copolymer*.sup.4
Carbon black 6 2 12 6 6 6 6 2 6 6
Yellow pigment*.sup.5 6
Magenta Pigment*.sup.6 6
Cyan pigment*.sup.7 6
Methyl ethyl ketone
80 80 80 80 80 80 80 80 80 80 80
Toluene 16
Isopropyl alcohol 64
Ethyl acetate 80
Softening point of vehicle (.degree.C.)
92 92 92 91 78 80 91 92 92 92 74 89 91
__________________________________________________________________________
*.sup.1 TPETGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
92.degree. C.
*.sup.2 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
89.degree. C.
*.sup.3 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, liquid
*.sup.4 Melt index: 2,500, softening point: 84.degree. C.
*.sup.5 Sanyo Color Works, Ltd., C.I. Pig. No. Y12
*.sup.6 Sanyo Color Works, Ltd., Cl. Pig. No. R122
*.sup.7 Sanyo Color Works, Ltd., CI. Pig. No. B15-2
Each of the inks shown in Table 1-1 was evaluated for heat resistance.
Further, with use of each of the obtained thermal transfer recording
materials, printing was performed and the resulting printed images were
evaluated for solvent resistance, scratch resistance and transferability.
The printing was performed using a thermal transfer type bar code printer
(B-30 made by TEC Corp.) under the following conditions:
Applied energy: 25.8 mJ/mm.sup.2
Printing speed: 2 inches/second
Platen pressure: "High"
Printing pattern: Checkered flag pattern
The results are shown in Table 1-2.
[Heat resistance]
About 10 mg of each ink after being evaporated to dryness and dried was
accurately weighed out with an electronic scales. After being subjected to
a heat treatment in an oven at 250.degree. C. for an hour, the weight of
the ink was again measured. The ink residue ratio defined by the following
formula was determined to evaluate the heat resistance of the ink. When
the ink residue ratio is not less than 80%, there is no problem in
practical use.
##EQU1##
[Solvent resistance]
As a receptor, there was used an aluminum-deposited polyethylene
terephthalate film having a pressure-sensitive adhesive layer on the
aluminum deposition layer side. Printed images (checkered flag pattern)
formed on the surface of the polyethylene terephthalate film were rubbed
ten times with a swab (cotton stick) impregnated with a solvent shown in
Table 1-2. The solvent resistance of the printed images was evaluated
according to the following criterion:
Evaluation criterion
A . . . The image is not removed at all.
B . . . The image is little removed.
C . . . The image is a little removed.
D . . . The image is appreciably removed. The evaluation value "A" or "B"
indicates that the printed images are practically usable.
[Scratch resistance]
With use of the same receptor employed in the solvent resistance test,
printing was performed and the resulting printed images (checkered flag
pattern) were subjected to the below-mentioned scratch resistance test.
The scratch resistance of the printed images was evaluated according to
the following criterion.
Test conditions
Tester: Rub Tester made by Yasuda Seiki Seisakusho Ltd.
Rubbing material: Sand eraser
Load: 250 g/cm.sup.2
Reciprocation number: 10
Evaluation criterion
A . . . The image is not changed at all.
B . . . The image is little changed.
C . . . A very slight portion of the image is removed.
D . . . An appreciable portion of the image is removed.
E . . . The image is removed, resulting in disappearing.
The evaluation value "A", "B" or "C" indicates that the printed images are
practically usable.
[Transferability]
As a receptor, there was used a 76 .mu.m-thick polyimide film formed on one
side thereof with a silicone resin type pressure-sensitive adhesive layer
and on the other side thereof with a white coating layer having the
following formula (coating amount: 28 g/m.sup.2). Hereinafter, this
receptor is referred to as "receptor A".
______________________________________
Components Parts by weight
______________________________________
Saturated polyester resin
5
Phenoxy resin 11
Titanium oxide 29
______________________________________
Printing was performed to form printed images (checkered flag pattern) on
the white coating layer of receptor A. The reflection optical density (OD
value) of the solid-printed portion of the image was measured with a
reflection densitometer (Macbeth RD 914) to evaluate the transferability.
When the OD value is not less than 0.8, there is no problem in practical
use.
TABLE 1-2
__________________________________________________________________________
Com. Com.
Com.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex. Ex. Ex. Ex.
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10
1-1 1-2 1-3
Ink residue ratio (%)
95 93 95 94 90 93 95 95 95 95 50 93 95
__________________________________________________________________________
Solvent resistance
Ethanol A A A B B B A A A A D B B
Kerosene A A A A A A A A A A D A A
Gasoline A A A A A A A A A A D A A
Toluene B B B B B B B B B B D B B
Carbon tetrachloride
A A A A A A A A A A D A A
Scratch resistance
B B B B B B c B B B E B B
OD value 1.90
1.70
1.78
1.75
1.70
1.40
1.80
2.05
2.08
2.00
1.85.
0.70 0.78
__________________________________________________________________________
With use of each of the thermal transfer recording materials obtained in
Examples 1-1 to 1-10, printed images were formed on the white coating
layer of receptor A by means of the same bar code printer as mentioned
above under the same printing conditions. The receptor A bearing the
printed images was placed in a drying oven (Model DX-58 made by Yamato
Scientific Co., Ltd.) and heated at 200.degree. C. for 60 minutes. With
respect to the printed images thus subjected to the heat treatment, the
solvent resistance, scratch resistance and transferability were evaluated
in the same manner as described above. The results are shown in Table 1-3.
TABLE 1-3
__________________________________________________________________________
Ex. 1-1
Ex. 1-2
Ex. 1-3
Ex. 1-4
Ex. 1-5
Ex. 1-6
Ex. 1-7
Ex. 1-8
Ex. 1-9
Ex. 1-10
__________________________________________________________________________
Solvent resistance
Ethanol A A A A A A A A A A
Kerosene A A A A A A A A A A
Gasoline A A A A A A A A A A
Toluene A A A A A A A A A A
Carbon tetrachloride
A A A A A A A A A A
Scratch resistance
A A A A A A A A A A
OD value 1.90
1.70
1.78
1.75
1.70
1.40
1.80
2.05
2.08
2.00
__________________________________________________________________________
EXAMPLES 1-11 AND 1-12 AND COMPARATIVE EXAMPLE 1-4
Onto the front side (the opposite side with respect to the
sticking-preventive layer) of the polyethylene terephthalate film was
applied a wax coating liquid having the formula shown in Table 1-4,
followed by drying to form a wax layer with a coating amount of 0.4
g/m.sup.2. Onto the wax layer was applied an ink coating liquid having the
same formula as that used in Example 1-1, followed by drying to form a
heat-meltable ink layer with a coating amount of 2 g/m.sup.2, yielding a
thermal transfer recording material.
The printed images obtained with use of each of the thus obtained thermal
transfer recording materials, which printed images were not subjected to
the heat treatment, were evaluated for the scratch resistance in the same
manner as in Examples 1-1 to 1-10. The results thereof are shown in Table
1-4.
TABLE 1-4
__________________________________________________________________________
Ex. 1-11
Ex. 1-12
Com. Ex. 1-4
__________________________________________________________________________
Formula of wax coating liquid (%)
Carnauba wax emulsion*.sup.1
33
(solid content: 30%)
Polyethylene wax emulsion*.sup.2
25
(solid content: 40%)
Paraffin wax emulsion*.sup.3 25
(solid content: 40%)
Methanol 67 75 75
Penetration of wax layer
less than 1
less than 1
12
Scratch resistance
A A E
__________________________________________________________________________
*.sup.1 Melting point: 84.degree. C.
*.sup.2 Melting point: 102.degree. C.
*.sup.3 Melting point: 74.degree. C.
As is apparent from Table 1-4, the thermal transfer recording materials of
Examples 1-11 and 1-12 wherein a wax layer having a penetration of not
more than 1 is provided is further improved in the scratch resistance as
compared to the thermal transfer recording material of Example 1-1. In
contrast thereto, the thermal transfer recording material of Comparative
Example 1-4 is rather degraded in the scratch resistance by providing the
wax layer. The reason therefor is presumed that since the penetration of
the used wax layer exceeds 1 (penetration: 12), the ink composed of the
epoxy resin is plasticized with the wax when heat is applied in the
thermal transfer.
EXAMPLE 1-13 AND COMPARATIVE EXAMPLE 1-5
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer were applied coating liquids for respective color inks shown in
Table 1-5, followed by drying to obtain a thermal transfer recording
material wherein respective color heat-meltable ink layers each having a
coating amount of 2 g/m.sup.2 were arranged as shown in FIG. 1.
TABLE 1-5
__________________________________________________________________________
Ex. 1-13 Com. Ex. 1-5
Yellow
Magenta
Cyan
Yellow
Magenta
Cyan
__________________________________________________________________________
Formula of ink coating liquid (%)
Epikote 1031S 14 14 14
Paraffin wax 12.5
12.5 12.5
Ethylene-vinyl acetate copolymer*.sup.1
1.5 1.5 1.5
Yellow pigment*.sup.2
6 6
Magenta pigment*.sup.3
6 6
Cyan pigment*.sup.4 6 6
Methyl ethyl ketone
80 80 80
Toluene 16 16 16
Isopropyl alcohol 64 64 64
Softening point of vehicle (.degree.C.)
92 92 92 74 74 74
__________________________________________________________________________
*.sup.1 Melt index: 2,500, softening point: 84.degree. C.
*.sup.2 Sanyo Color Works, Ltd., C.I. Pig. No. Y12
*.sup.3 Sanyo Color Works, Ltd., C.I. Pig. No. R122
*.sup.4 Sanyo Color Works, Ltd., C.I. Pig. No. B15-2
With use of each of the obtained thermal transfer recording materials,
superimposing-printing on one dot basis was performed in the order of
yellow, magenta and cyan under the printing conditions mentioned below.
With respect to the yellow ink dots formed on the receptor, the magenta
ink dots superimposed respectively on the yellow ink dots and the cyan ink
dots superimposed respectively on the magenta ink dots, the ratio of the
area of the ink dot to the area (0.0154 mm.sup.2) of one heat-generating
element (hereinafter referred to as "dot-transfer ratio") was determined.
The dot-transfer ratio is an average value of those for 193 dots.
Superimposing of ink dots is advantageously performed as the dot-transfer
ratio is nearer to 1. The results are shown in Table 1-6.
[Printing conditions]
Thermal transfer printer: B-30 made by TEC Corp.
Applied energy: 19.6 mJ/mm.sup.2
Printing speed: 2 inches/second
Platen pressure: "High"
Receptor: Aluminum-deposited polyethylene terephthalate film having a
pressure-sensitive adhesive layer on the aluminum deposition layer side
Evaluation criterion
A . . . Dot-transfer ratio: 0.95 to 1.05
B . . . Dot-transfer ratio: not less than 0.90 and less than 0.95
C . . . Dot-transfer ratio: less than 0.90
TABLE 1-6
______________________________________
Dot-transfer ratio
Yellow Magenta Cyan
ink dot ink dot ink dot
______________________________________
Ex. 1-13 A A A
Com. Ex. 1-5
A C C
______________________________________
As is apparent from Table 1-6, when different color ink dots are
superimposed one on another with use of the thermal transfer recording
material for color image formation according to the present invention,
favorable superimposing quality can be achieved.
EXAMPLES 2-1 TO 2-7 AND COMPARATIVE EXAMPLES 2-1 to 2-3
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer was applied an ink coating liquid having the formula shown in Table
2-1, followed by drying to form a heat-meltable ink layer with a coating
amount of 2 g/m.sup.2, yielding a thermal transfer recording material.
TABLE 2-1
__________________________________________________________________________
Com. Com.
Com.
Ex. 2-1
Ex. 2-2
Ex. 2-3
Ex. 2-4
Ex. 2-5
Ex. 2-6
Ex. 2-7
Ex. 2-1
Ex.
Ex.
__________________________________________________________________________
2-3
Formula of ink coating liquid (%)
Araldite ECN1280*.sup.1
14 18 8 11 11 7 12.6 5
Epikote 1003*.sup.2 3 7 14 9
Epikote 828*.sup.3 3
Paraffin wax 16
Ethylene-vinyl acetate copolymer*.sup.4 1.4 2
Carbon black 6 2 12 6 6 6 6 2 6 6
Methyl ethyl ketone
80 80 80 80 80 80 80 80
Toluene 16
Isopropyl alcohol 64
Ethyl acetate 80
Softening point of vehicle (.degree.C.)
80 80 80 82 67 85 80 74 89 86
__________________________________________________________________________
*.sup.1 oCresol novolak polyglycidyl ether made by AsahiCIBA Limited,
softening point: 80.degree. C.
*.sup.2 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
89.degree. C.
*.sup.3 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, liquid
*.sup.4 Melt index: 2,500, softening point: 84.degree. C.
Each of the inks shown in Table 2-1 was evaluated for the heat resistance
in the same manner as in Examples 1-1 to 1-10. Further, each of the thus
obtained thermal transfer recording materials was evaluated for the
solvent resistance and scratch resistance of printed images and the
transferability of the ink layer in the same manner as in Examples 1-1 to
1-10. The results thereof are shown in Table 2-2.
TABLE 2-2
__________________________________________________________________________
Com. Com.
Com.
Ex. 2-1
Ex. 2-2
Ex. 2-3
Ex. 2-4
Ex. 2-5
Ex. 2-6
Ex. 2-7
Ex. 2-1
Ex.
Ex. 2-3
Ink residue ratio (%)
95 94 95 93 90 93 95 50 93 95
__________________________________________________________________________
Solvent resistance
Ethanol A A A B B B A D a B
Kerosene A A A A A A A D A A
Gasoline A A A A A A A D A A
Carbon tetrachloride
A A A A A A A D A A
Scratch resistance
B B B B B B c E B B
D value 2.32
2.31 2.28
1.75 1.78
1.40 2.10
1.85 0.70
0.73
__________________________________________________________________________
With use of each of the thermal transfer recording materials obtained in
Examples 2-1 to 2-7, printed images were formed on the white coating layer
of receptor A by means of the same bar code printer as used in Examples
1-1 to 1-10 under the same printing conditions. The receptor A bearing the
printed images was placed in a drying oven (Model DX-58 made by Yamato
Scientific Co., Ltd.) and heated at 200.degree. C. for 60 minutes. With
respect to the printed images thus subjected to the heat treatment, the
solvent resistance, scratch resistance and transferability were evaluated
in the same manner as in Examples 1-1 to 1-10. The results are shown in
Table 2-3.
TABLE 2-3
__________________________________________________________________________
Ex. 2-1
Ex. 2-2
Ex. 2-3
Ex. 2-4
Ex. 2-5
Ex. 2-6
Ex. 2-7
__________________________________________________________________________
Solvent resistance
Ethanol A A A A A A A
Kerosene A A A A A A A
Gasoline A A A A A A A
Carbon tetrachloride
A A A A A A A
Scratch resistance
A A A A A A A
OD value 2.32
2.31
2.28
1.75
1.78
1.40
2.10
__________________________________________________________________________
EXAMPLE 2-8 AND 2-9 AND COMPARATIVE EXAMPLE 2-4
Onto the front side (the opposite side with respect to the
sticking-preventive layer) of the polyethylene terephthalate film was
applied a wax coating liquid having the formula shown in Table 2-4,
followed by drying to form a wax layer with a coating amount of 0.4
g/m.sup.2. Onto the wax coating layer was applied an ink coating liquid
having the same formula as that used in Example 2-1, followed by drying to
form a heat-meltable ink layer with a coating amount of 2 g/m.sup.2,
yielding a thermal transfer recording material.
The printed images obtained with use of each of the thus obtained thermal
transfer recording materials, which printed images were not subjected to
the heat treatment, were evaluated for the scratch resistance in the same
manner as in Examples 1-1 to 1-10. The results thereof are shown in Table
2-4.
TABLE 2-4
__________________________________________________________________________
Ex. 2-8
Ex. 2-9
Com. Ex. 2-4
__________________________________________________________________________
Formula of wax coating liquid (%)
Carnauba wax emulsion*.sup.1
33
(solid content: 30%)
Polyethylene wax emulsion*.sup.2
25
(solid content: 40%)
Paraffin wax emulsion*.sup.3 25
(solid content: 40%)
Methanol 67 75 75
Penetration of wax layer
less than 1
less than 1
12
Scratch resistance
A A E
__________________________________________________________________________
*.sup.1 Melting point: 84.degree. C.
*.sup.2 Melting point: 102.degree. C.
*.sup.3 Melting point: 74.degree. C.
As is apparent from Table 2-4, the thermal transfer recording materials of
Examples 2-8 and 2-9 wherein a wax layer having a penetration of not more
than 1 is provided is further improved in the scratch resistance as
compared to the thermal transfer recording material of Example 2-1. In
contrast thereto, the thermal transfer recording material of Comparative
Example 2-4 is rather degraded in the scratch resistance by providing the
wax layer. The reason therefor is presumed that since the penetration of
the used wax layer exceeds 1 (penetration: 12), the ink composed of the
epoxy resin is plasticized with the wax when heat is applied in the
thermal transfer.
EXAMPLES 2-10 AND COMPARATIVE EXAMPLE 2-5
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer were applied coating liquids for respective color inks shown in
Table 2-5, followed by drying to obtain a thermal transfer recording
material wherein respective color heat-meltable ink layers each having a
coating amount of 2 g/m.sup.2 were arranged as shown in FIG. 1.
TABLE 2-5
__________________________________________________________________________
Ex. 2-10 Com. Ex. 2-5
Yellow
Magenta
Cyan
Yellow
Magenta
Cyan
__________________________________________________________________________
Formula of ink coating liquid (%)
Araldite ECN 1280
14 14 14
Paraffin wax 12.5
12.5 12.5
Ethylene-vinyl acetate copolymer*.sup.1
1.5 1.5 1.5
Yellow pigment*.sup.2
6 6
Magenta pigment*.sup.3
6 6
Cyan pigment*.sup.4 6 6
Methyl ethyl ketone
80 80 80
Toluene 16 16 16
Isopropyl alcohol 64 64 64
Softening point of vehicle (.degree.C.)
80 80 80 74 74 74
__________________________________________________________________________
*.sup.2 Melt index: 2,500, softening point: 84.degree. C.
*.sup.2 Sanyo Color Works, Ltd., C.I. Pig. No. Y12
*.sup.3 Sanyo Color Works, Ltd., C.I. Pig. No. R122
*.sup.4 Sanyo Color Works, Ltd., C.I. Pig. No. B15-2
With respect to the thus obtained thermal transfer recording materials, the
dot-transfer ratio was determined in the same manner as in Example 1-13
and Comparative Example 1-5. The results thereof are shown in Table 2-6.
TABLE 2-6
______________________________________
Dot-transfer ratio
Yellow Magenta Cyan
ink dot ink dot ink dot
______________________________________
Ex. 2-10 A A A
Com. Ex. 2-5
A C C
______________________________________
As is apparent from Table 2-6, when different color ink dots are
superimposed one on another with use of the thermal transfer recording
material for color image formation according to the present invention,
favorable superimposing quality can be achieved.
EXAMPLES 3-1 TO 3-11 AND COMPARATIVE EXAMPLES 3-1 TO 3-4
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer was applied an ink coating liquid having the formula shown in Table
3-1, followed by drying to form a heat-meltable ink layer with a coating
amount of 2 g/m.sup.2, yielding a thermal transfer recording material.
TABLE 3-1
__________________________________________________________________________
Com.
Com.
Com.
Com.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex. Ex. Ex. Ex.
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-1 3-2 3-3 3-4
__________________________________________________________________________
Formula of ink coating liquid
(%)
Epikote 4007P*.sup.1
14 11 11 7 12.6
13.3 5
BPFDGE*.sup.2 14 11.9 10.5
BPFDGE*.sup.3 11
BPFDGE*.sup.4 11
BPFDGE*.sup.5 14
Epikote 1003*.sup.6
3 7 3 14 9
Epikote 828*.sup.7 3
Epikote 1031S*.sup.8 3
Paraffin wax 16
Ethylene-vinyl acetate 1.4
0.7 2.1 2 3.5
copolymer*.sup.9
Carbon black 6 6 6 6 6 6 6 6 6 6 6 2 6 6 6
Methyl ethyl ketone
80 80 80 80 80 80 80 80 80 80 80 80 80
Toluene 16
Isopropyl alcohol 64
Ethyl acetate 80
Softening point of vehicle
109
105
90 99 107
108
95 98 91 93 89.5
74 89 96 92
(.degree.C.)
__________________________________________________________________________
*.sup.1 BPFDGE made by Yuka Shell Epoxy Kabushiki Kaisha in which the
content of BPFDGE of formula (V) wherein ml = 0 is 0.85%, softening point
109.degree. C.
*.sup.2 BPFDGE in which the content of BPFDGE of formula (V) wherein ml =
0 is 0.44%, softening point; 95.degree. C.
*.sup.3 BPFDGE in which the content of BPFDGE of formula (V) wherein ml =
0 is 1.25%, softening point: 100.degree. C.
*.sup.4 BPFDGE in which the content of BPFDGE of formula (V) wherein ml =
0 is 1.95%, softening point: 92.degree. C.
*.sup.5 BPFDGE in which the content of BPFDGE of formula (V) wherein ml =
0 is 2.65%, softening point: 89.5.degree. C.
*.sup.6 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
89.degree. C.
*.sup.7 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, liquid
*.sup.8 TPETGE made by Yuka Shell Epoxy Kabushiki Kaiha
*.sup.9 Nippon UNICAR COMPANY LIMITED, melt index: 2,500, softening point
84.degree. C.
Each of the inks shown in Table 3-1 was evaluated for the heat resistance
in the same manner as in Examples 1-1 to 1-10. Further, each of the thus
obtained thermal transfer recording materials was evaluated for the
solvent resistance and scratch resistance of printed images and the
transferability of the ink layer in the same manner as in Examples 1-1 to
1-10. The results thereof are shown in Table 3-2.
TABLE 3-2
__________________________________________________________________________
Com.
Com.
Com.
Com.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex.
Ex. Ex. Ex. Ex.
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-1 3-2 3-3 3-4
Ink residue ratio (%)
96 95 93 94 94 95 96 93 93 95 95 50 93 95 93
__________________________________________________________________________
Solvent resistance
Kerosene A B B B A A A A A A A D B B B
Gasoline A A A A A A A A A A B D A A B
Ethanol A A A A A A A A A A B D A A A
Carbon tetrachloride
A A A A A A A A A A B D A A B
Toluene B B B B B B B B B B C D B B C
Scratch resistance
B B B B B B B B B B B E B B D
OD value 1.65
1.57
1.63
1.20
1.55
1.58
1.88
1.04
1.99
1.90
2.00
1.85
0.70
0.75
1.63
__________________________________________________________________________
With use of each of the thermal transfer recording materials obtained in
Examples 3-1 to 3-11, printed images were formed on the white coating
layer of receptor A by means of the same bar code printer as used in
Examples 1-1 to 1-10 under the same printing conditions. The receptor A
bearing the printed images was placed in a drying oven (Model DX-58 made
by Yamato Scientific Co., Ltd.) and heated at 200.degree. C. for 60
minutes. With respect to the printed images thus subjected to the heat
treatment, the solvent resistance, scratch resistance and transferability
were evaluated in the same manner as in Examples 1-1 to 1-10. The results
are shown in Table 3-3.
TABLE 3-3
__________________________________________________________________________
Ex. 3-1
Ex. 3-2
Ex. 3-3
Ex. 3-4
Ex. 3-5
Ex. 3-6
Ex. 3-7
Ex. 3-8
Ex. 3-9
Ex. 3-10
Ex.
__________________________________________________________________________
3-11
Solvent resistance
Kerosene A A A A A A A A A A A
Gasoline A A A A A A A A A A A
Ethanol A A A A A A A A A A A
Carbon tetrachloride
A A A A A A A A A A A
Toluene A A A A A A A A A A A
Scratch resistance
A A A A A A A A A A A
OD value 1.65
1.57
1.63
1.20
1.55
1.58 1.88 1.04 1.99 1.90 2.00
__________________________________________________________________________
EXAMPLES 3-12 TO 3-15 AND COMPARATIVE EXAMPLES 3-5 AND 3-6
Onto the front side (the opposite side with respect to the
sticking-preventive layer) of the polyethylene terephthalate film was
applied a wax coating liquid having the formula shown in Table 3-4,
followed by drying to form a wax layer with a coating amount of 0.4
g/m.sup.2. Onto the wax layer was applied an ink coating liquid having the
same formula as that used in Example 3-1, followed by drying to form a
heat-meltable ink layer with a coating amount of 2 g/m.sup.2, yielding a
thermal transfer recording material (Examples 3-12 and 3-13, and
Comparative Example 3-5). Onto the wax layer formed on the polyethylene
terephthalate film in the same manner as mentioned above was applied an
ink coating liquid having the same formula as that used in Example 3-7,
followed by drying to form a heat-meltable ink layer with a coating amount
of 2 g/m.sup.2, yielding a thermal transfer recording material (Examples
3-14 and 3-15, and Comparative Example 3-6).
The printed images obtained with use of each of the thus obtained thermal
transfer recording materials, which printed images were not subjected to
the heat treatment, were evaluated for the solvent resistance and scratch
resistance in the same manner as in Examples 1-1 to 1-10. The results
thereof are shown in Table 3-5.
TABLE 3-4
__________________________________________________________________________
Com.
Com.
Ex. 3-12
Ex. 3-13
Ex. 3-14
Ex. 3-15
Ex. 3-5
Ex. 3-6
__________________________________________________________________________
Formula of wax coating liquid (%)
Carnauba wax emulsion*.sup.1
33 33
(solid content: 30%)
Polyethylene wax emulsion*.sup.2
25 25
(solid content: 40%)
Paraffin wax emulsion*.sup.3 33 33
(solid content: 40%)
Methanol 67 75 67 75 67 67
Penetration of wax layer
less than 1
less than 1
less than 1
less than 1
12 12
__________________________________________________________________________
*.sup.1 Melting point: 84.degree. C.
*.sup.2 Melting point: 102.degree. C.
*.sup.3 Melting point: 74.degree. C.
TABLE 3-5
__________________________________________________________________________
Com.
Com.
Ex. 3-12
Ex. 3-13
Ex. 3-14
Ex. 3-15
Ex. 3-5
Ex. 3-6
Ink layer Ex. 3-1
Ex. 3-1
Ex. 3-7
Ex. 3-7
Ex. 3-1
Ex. 3-7
__________________________________________________________________________
Solvent resistance
Kerosene A A A A C C
Gasoline A A A A C C
Ethanol A A A A C C
Carbon tetrachloride
A A A A C C
Toluene A A A A D D
Scratch resistance
A A A A D E
__________________________________________________________________________
As is apparent from Table 3-5, the thermal transfer recording materials of
Examples 3-12 and 3-13 wherein a wax layer having a penetration of not
more than 1 is provided is further improved in the scratch resistance and
toluene resistance as compared to the thermal transfer recording material
of and Example 3-1, and the thermal transfer recording materials of
Examples 3-14 and 3-15 wherein a wax layer having a penetration of not
more than 1 is provided is further improved in the scratch resistance and
toluene resistance as compared to the thermal transfer recording material
of Example 3-7. In contrast thereto, the thermal transfer recording
material of Comparative Examples 3-5 and 3-6 are rather degraded in the
scratch resistance and toluene resistance by providing the wax layer. The
reason therefor is presumed that since the penetration of the used wax
layer exceeds 1 (penetration: 12), the ink composed of the epoxy resin is
plasticized with the wax when heat applied in the thermal transfer.
EXAMPLE 3-16 AND COMPARATIVE EXAMPLE 3-7
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer were applied coating liquids for respective color inks shown in
Table 3-6, followed by drying to obtain a thermal transfer recording
material wherein respective color heat-meltable ink layers each having a
coating amount of 2 g/m.sup.2 were arranged as shown in FIG. 1.
TABLE 3-6
__________________________________________________________________________
Ex. 3-16 Com. Ex. 3-7
Yellow
Magenta
Cyan
Yellow
Magenta
Cyan
__________________________________________________________________________
Formula of ink coating liquid (%)
Epikote 4007P 14 14 14
Paraffin wax 12.5
12.5 12.5
Ethylene-vinyl acetate copolymer*.sup.1
1.5 1.5 1.5
Yellow pigment*.sup.2
6 6
Magenta pigment*.sup.3
6 6
Cyan pigment*.sup.4 6 6
Methyl ethyl ketone
80 80 80
Toluene 16 16 16
Isopropyl alcohol 64 64 64
Softening point of vehicle (.degree.C.)
109 109 109
74 74 74
__________________________________________________________________________
*.sup.1 Melt index: 2,500, softening point: 84.degree. C.
*.sup.2 Sanyo Color Works, Ltd., C.I. Pig. No. Y12
*.sup.3 Sanyo Color Works, Ltd., C.I. Pig. No. R122
*.sup.4 Sanyo Color Works, Ltd., C.I. Pig. No. B15-2
With respect to the thus obtained thermal transfer recording materials, the
dot-transfer ratio was determined in the same manner as in Example 1-13
and Comparative Example 1-5. The results thereof are shown in Table 3-7.
TABLE 3-7
______________________________________
Dot-transfer ratio
Yellow Magenta Cyan
ink dot ink dot ink dot
______________________________________
Ex. 3-16 A A A
Com. Ex. 3-7
A C C
______________________________________
As is apparent from Table 3-7, when different color ink dots are
superimposed one on another with use of the thermal transfer recording
material for color image formation according to the present invention,
favorable superimposing quality can be achieved.
EXAMPLES 4-1 to 4-6 AND COMPARATIVE EXAMPLES 4-1 to 4-3
A 5 .mu.m-thick polyethylene terephthalate film was formed on one side
thereof with a sticking-preventive layer composed of a silicone resin with
a coating amount of 0.25 g/m.sup.2. Onto the opposite side of the
polyethylene terephthalate film with respect to the sticking-preventive
layer was applied an ink coating liquid having the formula shown in Table
4-1, followed by drying to form a heat-meltable ink layer with a coating
amount of 2 g/m.sup.2, yielding a thermal transfer recording material.
TABLE 4-1
__________________________________________________________________________
Com.
Com.
Com.
Ex. 4-1
Ex. 4-2
Ex. 4-3
Ex. 4-4
Ex. 4-5
Ex. 4-6
Ex. 4-1
Ex. 4-2
Ex. 4-3
__________________________________________________________________________
Formula of ink coating liquid (%)
Epikote 1003*.sup.1
14 14 14 11.9
13.3 14 9.8
Epikote 4003P*.sup.2 14
Paraffin wax 16
Ethylene-vinyl acetate copolymer*.sup.3
2.1 0.7 4.2 2
Printex 140V*.sup.4
6 6 6 6 6 6
MA 600*.sup.5 6
Special Black 100*.sup.6 6
#850*.sup.7 6
Methyl ethyl ketone
80 80 80 80 80 80 80 80
Toluene 16
Isopropyl alcohol 64
__________________________________________________________________________
*.sup.1 BPADGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
89.degree. C.
*.sup.2 BPFDGE made by Yuka Shell Epoxy Kabushiki Kaisha, softening point
76.degree. C.
*.sup.3 Melt index: 2,500, softening point: 84.degree. C.
*.sup.4 Carbon black made by Degussa AG. oil absorption: 110
*.sup.5 Carbon black made by Mitsubishi Kasei Corporation, oil absorption
130
*.sup.6 Carbon black made by Degussa AG., oil absorption: 94
*.sup.7 Carbon black made by Mitsubishi Kasei Corporation, oil absorption
78
Each of the inks shown in Table 4-1 was evaluated for the heat resistance
in the same manner as in Examples 1-1 to 1-10. Further, each of the thus
obtained thermal transfer recording materials was evaluated for the
solvent resistance and scratch resistance of printed images and the
transferability of the ink layer in the same manner as in Examples 1-1 to
1-10. The results thereof are shown in Table 4-2.
TABLE 4-2
__________________________________________________________________________
Com.
Com.
Com.
Ex. 4-1
Ex. 4-2
Ex. 4-3
Ex. 4-4
Ex. 4-5
Ex. 4-6
Ex. 4-1
Ex. 4-2
Ex. 4-3
Ink residue ratio (%)
93 93 92 90 91 93 93 93 50
__________________________________________________________________________
Solvent resistance
Kerosene A A A A A A A A D
Gasoline A A A A A A A A D
Ethanol B B B B B B B B D
Carbon tetrachloride
A A A A A A A A D
Scratch resistance
B B B B B B B D E
OD value 2.20
2.10
2.05
1.80
1.93
2.10
0.70
1.60
1.85
__________________________________________________________________________
With use of each of the thermal transfer recording materials obtained in
Examples 4-1 to 4-6, printed images were formed on the white coating layer
of receptor A by means of the same bar code printer as used in Examples
1-1 to 1-10 under the same printing conditions. The receptor A bearing the
printed images was placed in a drying oven (Model DX-58 made by Yamato
Scientific Co., Ltd.) and heated at 200.degree. C. for 60 minutes. With
respect to the printed images thus subjected to the heat treatment, the
solvent resistance, scratch resistance and transferability were evaluated
in the same manner as in Examples 1-1 to 1-10. The results are shown in
Table 4-3.
TABLE 4-3
__________________________________________________________________________
Ex. 4-1
Ex. 4-2
Ex. 4-3
Ex. 4-4
Ex. 4-5
Ex. 4-6
__________________________________________________________________________
Solvent resistance
Kerosene A A A A A A
Gasoline A A A A A A
Ethanol A A A A A A
Carbon tetrachloride
A A A A A A
Scratch resistance
A A A A A A
OD value 2.20
2.10 2.05 1.80 1.93
2.10
__________________________________________________________________________
EXAMPLES 4-7 AND 4-8 AND COMPARATIVE EXAMPLE 4-4
Onto the front side (the opposite side with respect to the
sticking-preventive layer) of the polyethylene terephthalate film was
applied a wax coating liquid having the formula shown in Table 4-4,
followed by drying to form a wax layer with a coating amount of 0.4
g/m.sup.2. Onto the wax layer was applied an ink coating liquid having the
same formula as that used in Example 4-1, followed by drying to form a
heat-meltable ink layer with a coating amount of 2 g/m.sup.2, yielding a
thermal transfer recording material.
The printed images obtained with use of each of the thus obtained thermal
transfer recording materials, which printed images were not subjected to
the heat treatment, were evaluated for the solvent resistance and scratch
resistance in the same manner as in Examples 1-1 to 1-10. The results
thereof are shown in Table 4-4.
TABLE 4-4
__________________________________________________________________________
Ex. 4-7
Ex. 4-8
Com. Ex. 4-4
__________________________________________________________________________
Formula of wax coating liquid (%)
Carnauba wax emulsion*.sup.1
33
(solid content: 30%)
Polyethylene wax emulsion*.sup.2
25
(solid content: 40%)
Paraffin wax emulsion*.sup.3 25
(solid content: 40%)
Methanol 67 75 75
Penetration of wax layer
less than 1
less than 1
12
Solvent resistance
A A D
Kerosene A A D
Gasoline A A D
Ethanol A A D
Carbon tetrachloride
A A D
Scratch resistance
A A D
__________________________________________________________________________
*.sup.1 Melting point: 84.degree. C.
*.sup.2 Melting point: 102.degree. C.
*.sup.3 Melting point: 74.degree. C.
As is apparent from Table 4-4, the thermal transfer recording materials of
Examples 4-7 and 4-8 wherein a wax layer having a penetration of not more
than 1 is provided is further improved in the scratch resistance and
ethanol resistance as compared to the thermal transfer recording material
of Example 4-1. In contrast thereto, the thermal transfer recording
material of Comparative Example 4-4 is rather degraded in the scratch
resistance and solvent resistance by providing the wax layer. The reason
therefor is presumed that since the penetration of the used wax layer
exceeds 1 (penetration: 12), the ink composed of the epoxy resin is
plasticized with the wax when heat is applied in the thermal transfer.
In addition to the materials and ingredients used in the Examples, other
materials and ingredients can be used in Examples as set forth in the
specification to obtain substantially the same results.
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